Miniature electrochemical cells are useful in applications such as chemical sensing wherein the electrodes of a strip element interface with an electronic device. The electronic device, often termed a meter, measures the electrical response of the strip element to the sample and can also supply power to the strip element to perform a test. In order to perform these functions, the strip element electrodes must be able to make electrical connection to the meter circuitry. Such an electrical connection may be made via a connection device on the meter which mates with areas on the strip element in electrical communication with the electrochemical cell electrodes.
In configurations of electrochemical cells as disclosed in WO 98/43073, U.S. Pat. No. 5,437,999, EP 0 964 059 A2, WO 00/20626, an upper and a lower electrode face oppose one another with an electrically insulating layer between them. The electrodes in such a configuration are typically formed on separate substrates that are assembled during manufacture of the electrochemical cell. This configuration presents difficulties in manufacture when forming a part by which the strip element electrodes are connected to the meter circuitry, as it is different from the usual connection configuration where the connection areas are all on the same plane.
The issue of connection areas in different planes has been addressed in various ways. In WO 98/43073, a method and device are disclosed wherein cut-outs are formed in one of the electrode layers and in the insulating layer to expose an area of the underlying electrode layer which can be used as an connection area. In U.S. Pat. No. 5,437,999 and WO 00/20626, a method an device are disclosed wherein a flap is formed on one electrode layer with a corresponding cut-out in the other electrode layer to expose a suitable connection area. In this configuration, the insulating layer is cut short so as not interfere with the connection area.
In EP 0 964 059 A2, the insulating layer is cut short, and a hole is formed in the upper substrate in order to expose a connection area at the base of the well that is formed. The well may be filled with a conductive material and a contact made with the conductive material at the top of the filled well, thus bringing the connection areas onto one plane.
A drawback to these configurations is that they require features on more than one of the cell layers to be in registration with one another when the layers are assembled into a working device. This creates difficulties in manufacturing the devices and limits the manufacturing techniques that can be used. In particular, for costs and throughput considerations, it is often desirable to manufacture the strip elements in a continuous web form. When using continuous webs it is often difficult to reliably achieve the down-web registration of repeating features formed on different layers prior to a lamination step. Often this requires expensive control systems and a relatively fragile fabrication process, if it is possible at all.